Nitric acid oxidation of fatty materials



Patented Dec.1 9, 19 44 UNIT-ED STAT Es PATE T orrica NITRICACID- OXIDATION or ram l MATERIALS Donald Price, New York, N. Y., and Richard Grifflth, Little Silver, N.- J., ass tliors to National- Oil Products Company, Harrison, N. 1., a corporation of New Jersey No Drawing. Application October 15, 1941,

' Serial No. 415,086

Claims. (Cl. 260-406)- This invention relates to the oxidative scission of .unsaturated and hydroxylated fatty compounds, and particularly to the oxidation of such compounds to form lower. mono and dibasic acids. .It has heretofore been proposed to subject unsaturated fatty acids to the action of nitric acid,- whereby to cut the fatty chains at the unsaturated linkages and to form mono and dibasic acids from the segments of the cut fatty chains. To accelerate this reaction, there have been proposed various catalysts such as compounds of mercury, copper, iron, and latterly, vanadium However, it is impossible, even with the use of these catalysts, to obtain high yields of the mono and dibasic acids orto obtain even moderate yields in a reaction of reasonably short duration- Accordingly, it is an object of this invention to provide a process for'oxidativescission of fatty materials which will give high yields of desirable products.

Another object is to provide a' process for oxidative scission of fatty materials which will not require an excessive lengthof time.

Still another object is to provide a process by which hydroxylated fatty materials, as well as unsaturated fatty materials, may be subjected to acid; IO-hydroxy stearic acid; ricinoleic acid,

9,10-dihydroxy stearic acid; 9 or IO-hydroxy palmitic acid;'9-hydroxy stearic acid, 13 or 14- hydroxy behenic acid and the like. Examples'of suitable unsaturated acids are oleic acid, brassidic acid, erucic acid, linoleic acid, eleostearic acid, linolenic acid, clupanodonic acid and the like.

Instead of the pureacids there may be em-- ployed the mixed acids derived by hydrolysis of unsaturated and/or hydroxylated fats and oils,

such as, for instance, the fatty acids derived by hydrolysis of castor oil, olive oil, hydrogenated castor oil, sardine oil and the like. Suitable fatty acids may likewise be produced by the hydrolysis of fatty materials which have been proc essed to develop hydroxyl or unsaturated groups therein, for instance wet-blown oils and fats or ox'idative scission to yield mono and dibasic acids:

- The above and other-objects are attained by this invention in a process which involves treating a hydroxylated, and/or unsaturated fatty starting material with nitric acid in the presence of a catalyst comprising a manganese compound.

The fatty chains of the fatty materials are there by cut at the unsaturated or hydroxyl-carrying carbons, and the carbons at the cut ends oxidized to carboxyl groups with the formation of mono and dicarboxylic acids. The fatty acids are separated from each other and from the unreacted materials and by-products by any suitable means, such as extraction, steam distillation or the like.

Referringto the hydroxylated and/or unsaturated fatty starting material, this may be any oil, fat', fatty acid or fatty ester containing fatty chains having carbinol or unsaturated groups in-.

Examples of suitoils and fats which have been sulfonated and subjected tohydrolytic desulfonation. Examples:

of oils which when wet-blown may serve as sources of fatty acids suitable as starting materials in the process of this invention are cottonseed oil, com'oil, coconut oil, lard oil, peanut oil and the like. Examples of oils which when sulfonated and hydrolyticallydesulfonated may serve as sources of fattyacids' suitable as starting; materials in the process of this invention are olive oil, s'oyabean oil, castor oil, teaseed oil, sardine oil, train oil and the like.

Obviously, instead of pure esters there may be employed as starting materials in the process of this invention mixtures ofsuitable esters such,

for example, as the'natural and processed fats and 'oils'named ,above as sources of fatty acids.

Referring to the manganese catalyst compound, this may most advantageously be supplied as manganese dioxide. However, insteadof main 4 ganese dioxide, any manganous or manganic salt,

, or any manganese oxide, or any salt of any man ganese-containing acid radical, may be employed.

Examples of suitable manganese compounds coming within the above requirements are manganou's. chloride, manganic nitrate, manganous oxide,

' manganic oxide, manganese trioxide, manganese with the fatty material to be oxidized, heating the mixture to between about and 120 C.,

heptoxide, potassium permanganate,

manganitef and the like. p v The oxidationreaction is'preferably carried out by mixing the manganese catalyst compound preferably between and C. and thereafter slowlyadding nitric acid with stirring; .The

Y nitric acid should be added with extremelslownesslat first, until the induction period is over. The temperatureis maintained between 60 d employed will vary upwards of about 60% and should preferably be between about 65% and about 71 The monobasic acidsmay be recovered from the reaction mixture by steam distillation. In this case the reaction mixture, after dilution to arrest the reaction, is neutralized with a suitable base, slightly acidified, then subjected to steam distillation, the monobasic acids coming over with the steam, leaving behind the dibasic acids, byproducts and unreacted material.

The dibasic acids are preferably recovered from the steam distillation residue by a process depending upon the solubility of the dibasic acids in slightly acid solution. -It has been discovered that the dibasic acids dissolve in solutions which have a sufficiently high acidity to suppress solution of the monobasic'aci'ds and other materials in the residue. A pH between'about 5.5 and about 6.5 will usually effect solution of the dibasic acids, while suppressing solution of the other constituents, but obviously this will vary with the materials treated and can best be determined in each individual case by experiment. The separation process based upon the principles above carried out much more expeditiously than any of the heretofore known processes for oxidative scission of fatty materials. With the above discussion in mind, there are given hereinafter examples of procedures according to this invention, which examples are to be taken as illustrative merely, and not in any limiting sense. All parts given are by weight.

Example I 30 parts of the fatty acids derived by hydrolysis of hydrogenated castor oil were melted and .3 part of MnOa were mixed in at 113 C. 95 parts of 70% HNO: were then added slowly, with continuous stirring, the first portions being added dropwise until the reaction was going smoothly. The mixture was maintained at 105 C, for 4 /2 hours. The mixture was then cooled, diluted with 300 parts of water, neutralized with NaOH and then slightly acidified. The acidified mixture was steam distilled and7 parts of monoset forth may be carried out by. adjusting the pH' of the steam distillation residue to a value (usually between about 5.5 and about 6.5)' such as to cause the dibasic acids to dissolve in the aqueous phase; thereafter removing the aqueous solution of the dibasicacids from the undissolved residue; and finally reacidifylng the aqueous solution to cause the dibasic acids to be thrown out of solution. The dibasic acids are then, removed and dried.

The dibasic acids may also be recovered from the steam distillation residue by any other suitable process such as a selective solvent extraction process. For instance, the residue may be extracted first with a non-polar, or relatively basic acids, largely caproic acid, were recovered. The residue from the steam distillation was extracted with 150 parts of petroleum ether (boiling range 35 to 70 C.) to remove the unreacted fatty materials and by-products. The extracted residue was then re-extracted with ethyl acetate, and the extract solution evaporated to leave 19 parts of a white solid consisting principally of mixed decane dicarboxylic and nonanedicarboxylic acids. The mixed dicarboxylic acids melted between 95 C. and 108 C.

Example II 60 parts of IO- hydroxy stearic acid (produced by the sulfonation and hydrolysis of oleic acid) were melted and heated to 90 C., and .3 part of mo: were added. 95 parts of 70% HNOa were then added slowly with continuous stirring, the

40 flrstportions being added dropwise until the reslightly polar, solvent such as a petroleum fraction to remove'the unreacted oil and by-products wtihout dissolving the, dibasic acids. Thereafter the residue may be extraced with a relatively more highly polar solvent, such as ethyl acetate, to dissolve the dibaslc acids. Upon evaporation of the polar solvent extraction solution, the dibasic acidsare left as a technically pure product. This product may be further refined and purified by recrystallization or other means.

A petroleum fraction was cited above as a suitable non-polar solvent; however, ethylene dichlo ride, chloroform, cold benzene, cold ether and other solvents of like character may be employed.

Ethyl acetate was cited as a suitable relatively highly polar solvent; however, butanol, hot wa ter, hot methanol, hot ethanol, hot ether or-the like may be substituted therefor.

'was maintained at 90 C. for 3 /2 .hours.

action was proceeding smoothly. The mixture The resultant oxidized mass was then cooled, diluted, neutralized, reacidified, steam distilled, and ,extracted with petrolem ether and ethyl acetate exactly as in Example I. There were recovered Example III 60 parts of the fatty acids derived by hydrolysis of castor oil and 1 part MnOz were mixed and heated to 100 C. 190 parts 013 HNO; were added slowly, using the same precautions as were exercised in the preceding examples. The mass was maintained between C. and C. for 5 /2 hours. The resultant oxidized mass was then cooled, diluted with 300 parts of water, and suificient 10% NaOH added to leave the mass only slightly acid. The mass was then subjected to steam distillation, and 13 parts of monobasic acids were recovered in the distillate. The pH of the residue from the distillation was adjusted with NaOH to 6.5, whereupon the monosodium salts of the dibasic acids passed into solution and the unreacted fat and by-products were thrown out of solution. The solution was The process as above outlined commonly pro-1 duces yields in excessof 60% of the theoretical, and in the treatment of hydroxylated fatty materials produces yields in excess of 70% or 80% of the theoretical. Further, the process may be 31 parts of 9.10-dihydroxy stearic acid were melted and heated to 100 C. and .5 part 01 asea'aoo Milo. were" added. 4': parts of 70% i-INO': were stirred in width the same precautions as in the preceding examples, and the mixture heated to 110C. for 5 hours. The resultant masswas cooled, diluted, partially neutralized, steam distilled and adjusted to a pH of 6.5, and the solution removed and acidified exactly as in Example 111. There were recovered 6 parts of monobasi'c the group consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles.

- 6'. Process-foroxidizing fatty'substances contalning the fatty residues of oleic acid, which comprises treating said substances with nitric acid-in acids and 10 parts of mixed dibasic acids -(most'- ly azelaic and suberic acids). The mixed dibasic acids melted between 106 and 125 C.

Example V the" presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides andsalts of manganesecontaining .acid radicles. 1

"l. Process for oxidizing fatty acids containing residues chosen from the group consisting of'hy- 56 parts of oleic acid and .6 parts of mo;

- were mixed and heated to 80 C; 190 partsof-i- 70% HNOa were added with the same precautions as inthe other examples. maintained at 80 C..for d-hours. 'Iheresultant masswas cooled, diluted, partially neutralized, steam distilled, and adjusted to a pH of 6.5, and

The temperature-wasthesolution removed and reacidiiied exactly asin E'xample 111. There were recovered 5 parts of monobasic acids and 14. parts of mixed dibasic acids (mostly azelaic and suberic acids), these mixed acids melting between 65 C. and 77 C. After recrystallization from benzene, the mixed dibasic acids melted between 88 C. and 102 C.

Itwill thus be seen that there is provided byxthis invention a process for oxidizing fatty materials, and especially hydroxylated fatty materials, to produce short chain mono and dibasic acids in much higher yields than are obtained by older processes. Further, the processes of this invention can be carried out very much more expeditiously than any older processes. 1

Since certain changes in carrying out the above process may be made without departing from its scope, it is intended thatall matter contained in the above description shall be interpret d as illustrative and not in a limiting sense.

Having described our invention what we claim as new and desire to secure by Letters Patent is: v

1. Process for oxidizing fatty substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles. 3'

2. Process for oxidizing fatty substances containing hydroxylated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides and s containing acid radicles.

3. Process for oxidizing fatty s alts of manganeseubstances containing the fatty residues of hydroxystearic acid,

which comprises treating said substances with nitric acid in the presence of a compound'se lected from the group consisting of manganous prises treating said substances-with nitric 'acid.

in the presence of a compound selected from droxylated and unsaturated fatty residues, which comprises treating said acids with nitric acid in the presence of a com ound selected from the group consisting ofmanganous'salts, manganic salts, manganese oxides and salts of manganesecontaining acid radicles.

- 8. Process foroxidizingfatty acids containing hydroxylated fatty residues, which comprises treating said-acids with nitric acid in the presence of a compound selected from theg'roup consisting of manganous salts, manganic salts, manganese oxides and salts :of manganese-containing acid'radicles. u 9-. Process which comprises treating hydroxystearic, acid with nitric acid in the presence of acompound selected from the group consisting of manganous salts, manganic salts,- manganese oxides and'salts of.-manganese-containing acidradicles.

10. Process which comprises treating dihy droxystearic acidwith nitric acid in the presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles.

11. Process for oxidizing fatty acids containing unsaturated fatty residues, which comprises treating said acids with nitric acid in the presence of a compound selected from the group con! sisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing 2 acid radicles. I

12. Process which comprises treating oleic acid with nitric acid in the presence of a compound selected from the sroup consisting of manganous salts, manganic salts. manganese oxides and salts of manganese-containing acid radicles.

18. Process for oxidizing fatty substances containlng residueschosen from the group consisting of hydroxylated and unsaturated fatty resi-, dues, which comprises treating said substances with nitric acidin the presence 'of manganese dioxide;

14.. Process for oxidizing fattysubstancescontaining" hydroxylated fatty residues, which comprises treating said substances with nitric acid a in the-"presence of manganese dioxide.

15 .Process for producing mono and dibasic acids from fatty substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of acompound selected from the group "consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles; and separating from the resultant oxidized mass-the monobasic. and dibasic acids formed bythe oxidation of the fatty substances.

16. Process for producing mono and dibasid" acids from fatty substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group taining acid radicles; and subjecting the resultant consisting oi manganous salts, manganic salts,

manganese oxides and salts of manganese-containing acid radicles; separating the monobasic acids from the resultant oxidized mass and extracting the residue of the oxidized mass with a non-polar organic solvent to remove the unreacted fatty materials and lay-products; and further extracting said residue with a polar organic solvent to recover the dibasic acids therefrom.-

and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles; separating the monobasic acids from the resultant oxidized mass; adjusting the pH of the residual mass to a value sufliciently high to effect solution of the dibasic acids in the aqueous phase of the mass, but suilicientiy low to suppress solution of the other materials; and separating from the mass the aqueous phase containing the dibasic acids.

18. Process for producing mono and dibasic acids from fatty substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group consisting of manganoussalts, manganic salts, man anese oxides and salts of manganese-conoxidized mass to steam distillation to separate the monobasic acids therefrom.

19. Process for producing mono and dibasic acids from fatty-substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a compound selected from the group consisting of manganous salts, manganic salts, manganese oxides and salts of manganese-containing acid radicles; subjecting the resultant oxidized mass to steam distillation to separate the monobasic acids therefrom; extracting the distillation residue with a non-polar organic solvent to remove the unreacted fatty materials and by-products; and further extracting the distillation residue with a' polar organic solvent to recover the dibasic acids therefrom.

20. Process for producing mono and dibasic acids from fatty substances containing residues chosen from the group consisting of hydroxylated and unsaturated fatty residues, which comprises treating said substances with nitric acid in the presence of a manganese compound; subjecting the resultant oxidized mass to steam distillation to separate the monobasic acids therefrom; adjusting the pH of the residual mass to a value sufliciently high to client solution of the dibasic acids in the aqueous phase of the mass, but sufiiciently low to suppress solution of the other materials; and separating from the mass the aqueous phase containing the dibasic acids.

DONALD PRICE.

RICHARD GRIFFITH. 

